A front jaw of the abovementioned type has become know, for example, from AT 376 576 and its corresponding U.S. Pat. No. 4,478,426. The sole holders in this known front jaw are supported on a common bolt which is loaded by the release spring through a pull rod, the pull rod being movably guided in a bore provided in the housing and extending in a longitudinal direction.
Furthermore, a front jaw with diagonal release capability is already known from an Austrian patent application of the Applicant with the reference AT-PS 396 337 and its corresponding U.S. Pat. No. 5,333,891. The sole holders are pivotally supported on a bearing block in such a front jaw, which bearing block is supported and guided on the housing. The sole holders are loaded through a center opening in this bearing block through a release plate by the spring force of the release spring. The bearing block is furthermore guided at its lower end by a recess and a wedge-shaped projection received therein so that the bearing block, after moving through a predetermined release path, can also swing-out laterally, thus enabling a diagonal release of the front jaw.